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ORGANIC  ANALYSIS

Qualitative Examination.
Carbon and Hydrogen.óCarbon compounds are fre-
quently inflammable, and when heated on platinum foil take
fipe or char and burn away. A safer test is to heat the substance
with some easily reducible metallic oxide, the oxygen of which
forms carbon dioxide with the carbon present. Take a piece of
soft glass tube about 13 cm. (5 in.) long, and fuse it together
at one end. Heat a gram or two of fine copper oxide in a
porcelain crucible for a few minutes to
drive off the moisture, and. let it cool
in a desiccator. Mix it with about
one-tenth of its bulk of powdered sugar
in a mortar. Pour the mixture into
the tube, the open end of which is now
drawn out into a wide capillary and
bent at the same time into the form                FIG. i.
shown in Fig.   i.     This is done by
shaking down the mixture to the closed end and revolving the
tube in the blow-pipe flame about 2^ cm. (i in.) beyond the
mixture until it is thoroughly softened. The tube is then
removed from the flame, drawn out gently and bent. Make a
file scratch across the end of the capillary and break it. When
the. tube is cold tap it horizontally at the edge of the bench, so
as to &rm a free channel above the mixture. Suspend it by a
COHEN'S ADV. p. o. c.                                               B